scholarly journals Main-chain scission of individual macromolecules induced by solvent swelling

2019 ◽  
Vol 10 (24) ◽  
pp. 6125-6139 ◽  
Author(s):  
Daniel Messmer ◽  
Oscar Bertran ◽  
Reinhard Kissner ◽  
Carlos Alemán ◽  
A. Dieter Schlüter
Keyword(s):  
Main Chain ◽  
Chain Scission ◽  
Comprehensive Investigation ◽  
Dendronized Polymers ◽  
Solvent Swelling

We present a comprehensive investigation of main-chain scission processes affecting peripherally charged and neutral members of a class of dendronized polymers (DPs) studied in our laboratory.

EXPERIMENTAL VALIDATION OF THE CHARLESBY AND HORIKX MODELS APPLIED TO DE-VULCANIZATION OF SULFUR AND PEROXIDE VULCANIZATES OF NR AND EPDM

2016 ◽  
Vol 89 (4) ◽  
pp. 671-688 ◽  
Author(s):  
M. A. L. Verbruggen ◽  
L. van der Does ◽  
W. K. Dierkes ◽  
J. W. M. Noordermeer
Keyword(s):  
Experimental Validation ◽  
Main Chain ◽  
Sol Gel ◽  
Chain Scission ◽  
Cross Linking ◽  
Cross Link ◽  
Practical Reality ◽  
Cross Links ◽  
The Cross ◽  
Theoretical Considerations

ABSTRACT The theoretical model developed by Charlesby to quantify the balance between cross-links creation of polymers and chain scission during radiation cross-linking and further modifications by Horikx to describe network breakdown from aging were merged to characterize the balance of both types of scission on the development of the sol content during de-vulcanization of rubber networks. There are, however, disturbing factors in these theoretical considerations vis-à-vis practical reality. Sulfur- and peroxide-cured NR and EPDM vulcanizates were de-vulcanized under conditions of selective cross-link and random main-chain scissions. Cross-link scission was obtained using thiol-amine reagents for selective cleavage of sulfur cross-links. Random main-chain scission was achieved by heating peroxide vulcanizates of NR with diphenyldisulfide, a method commonly employed for NR reclaiming. An important factor in the analyses of these experiments is the cross-linking index. Its value must be calculated using the sol fraction of the cross-linked network before de-vulcanization to obtain reliable results. The values for the cross-linking index calculated with sol-gel data before de-vulcanization appear to fit the experimentally determined modes of network scission during de-vulcanization very well. This study confirms that the treatment of de-vulcanization data with the merged Charlesby and Horikx models can be used satisfactorily to characterize the de-vulcanization of NR and EPDM vulcanizates.

OH Radical-Induced Main-Chain Scission of Poly(Ribonucleic Acids) under Anoxic Conditions

1983 ◽  
Vol 38 (1-2) ◽  
pp. 100-106 ◽  
Author(s):  
Komei Washino ◽  
Otmar Denk ◽  
Wolfram Schnabel
Keyword(s):  
Light Scattering ◽  
Main Chain ◽  
Degradation Mechanism ◽  
Chain Scission ◽  
Oh Radicals ◽  
Ribonucleic Acids ◽  
Chemical Mechanisms ◽  
Dilute Aqueous Solution ◽  
Ribose Moiety ◽  
Rayleigh Light

Poly(ribonucleic acids), poly A, poly C and poly U, were irradiated in O2-free dilute aqueous solution at pH 7 to 8 with single pulses (50 to 200 ns) of 16MeV electrons. With the aid of Rayleigh light scattering measurements main-chain scission, induced by OH radicals, was observed with the three polynucleotides. From the time dependence of the decrease of the light scattering intensity (LSI), the existence of two modes of decrease was inferred, indicating at least two different chemical mechanisms were operative in main-chain degradation. Evidence for the assignment of the slow mode of LSI decrease to the lifetime of a free radical was obtained from quenching experiments with cysteamine. It is noteworthy, that the extent and the lifetime of LSI decrease are not the same for the three polynucleotides. The differences indicate the influence of the chemical nature of the bases on main-chain scission. Consequently, it is concluded that OH attack at carbons in 1′ and/or 2′ position of the ribose moiety contributes essentially to the degradation mechanism.

A novel main chain scission type photoresists for EUV lithography

2020 ◽  
Author(s):  
Akihide Shirotori ◽  
Manabu Hoshino ◽  
Danilo De Simone ◽  
Geert Vandenberghe ◽  
Hirokazu Matsumoto
Keyword(s):  
Main Chain ◽  
Chain Scission ◽  
Euv Lithography
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